1. Field of the Invention
This invention relates to a method of manufacturing a semiconductor device, and in particular, to a method of manufacturing a semiconductor device having a damascene wiring wherein a conductive material is buried in a low dielectric constant insulating film.
2. Description of the Related Art
In the manufacturing process of a semiconductor device, it has been necessary, in order to remove fine particles adhering to the semiconductor substrate, to employ physical washing means together with chemical washing means. However, it has been impossible to reliably remove fine particles when the fine particles include very fine particles.
Under the circumstances, it has been proposed to employ an inorganic alkaline solution in order to remove abrasive particles from the surface of a Cu film after the Cu film has been buried in an insulating film by chemical mechanical polishing (CMP). Since CuO generated on the surface of a Cu film as a result of the polishing process of a Cu film, an electrostatic repulsive force generated between the CuO and the abrasive particles when an inorganic alkaline solution is sprayed onto the Cu film. As a result, the abrasive particles are prevented from adhering to the CuO layer.
Further, there has also been proposed a washing method using an organic alkaline washing liquid for washing a semiconductor substrate after the process of CMP for burying a conductive member made of Cu or a Cu alloy in an insulating film. Since an organic acid is included in a polishing material composition to be employed in the CMP, a layer of copper complex is formed on the surface of the conductive member due to the effect of this organic acid. Since this copper complex can be readily washed with the employment of an organic alkaline washing liquid, there is little possibility of damaging the buried wiring.
As for the interlayer insulating film in which a Cu film is to be buried, there have been conventionally employed a TEOS film, a silicon oxide film, a boro-phospho silicate glass film (BPSG film), a phospho silicate glass film (PSG film), etc. Recently, a low dielectric constant insulating film (a low-k insulating film) having a relative dielectric constant of 3.5 or less has been employed as an interlayer insulating film. This low-k film however is lower in mechanical strength than the materials that have been conventionally employed as an interlayer insulating film. Further, when the conventional washing method is applied to the low-k film in order to remove the fine particles adhering to the surface of Cu film, new defects may form on the surface of Cu film, resulting in reduced yield.